This invention relates to optimization of batch process where a plurality of batch processing lines are simultaneously used and the same batch process is repeatedly used to meet the required total amount of product to be made in the following downstream manufacturing process, which are used in the industry such as chemical industry, food industry or photographic industry.
Typically in manufacturing photographic materials, batch process is usually used because a great variety of raw materials is used, many kinds of coating liquids must be simultaneously prepared for carrying out simultaneous multi-coating and change of the raw material or prescription of the coating liquid are frequently made.
FIG. 4 shows a schematic diagram of conventional coating liquid preparation system used in a manufacturing process of photographic materials. The system includes Multi-purpose chemical liquid preparation vessels 13-1, 13-2, 13-3 and others (not shown), chemical liquid stock vessels 12-1, 12-2, . . . , and others (not shown), chemical liquid feeding pipe lines 11 and coating liquid preparation vessels 10-1 to 10-n. Each one of the multi-purpose chemical liquid preparation vessels is usually connected to a plurality of the chemical liquid stock vessels, for example, vessel 13-1 is connected to three different stock vessels 12-1, 12-2 and 12-3. Each one of stock vessels is connected to the pipe line 11 some of which are connected to a plurality of coating liquid preparation vessels by branching which need the common chemical liquid. The number of the coating liquid preparation vessels corresponds to the number of layers to be simultaneously coated on a photographic substrate to make photographic film. To make the system operative, a lot of automatic valves and liquid measuring devices are installed. Whenever the prescription of coating liquid is changed, the pipe line connection has to be changed by changing or increasing the pipe line branch together with related valves and measuring devices.
(1) Japanese Laid-open Patent Publication (JP-A) 095700/92 (tokkai-hei 04-095700) shows chemical liquid distribution process and apparatus where chemical liquid in a vessel is distributed to a plurality of vessels for preparing required solution such as coating solution via a common conduit and branches with valves therefrom. In this system, the common conduit is inclined to make it easy to clean the chemical liquid vessel and the common conduit separately and simultaneously at the change-over of the chemical liquid, which leads to reducing cleaning time and amount of cleaning liquid.
(2) In JP-A 071699/95 (tokkai-hei 07-071699), it is proposed to provide an automatic pipe-connecting device in a feed-line switching station, which is disposed between stock tanks and chemical fluid measuring devices located downstream next to the stock tanks, in order to reduce the number of feed-line switching valves, to prevent a fluid of different kind from mixing generated when switched connection of piping and minimize a fluid amount left in the piping.
(3) U.S. Pat. No. 5,339,875 (corresponding to JP-A 305232/93 (tokkai-hei 05-305232)) shows, in order to avoid complicated liquid feed-line, a method for the preparation of a liquid for supplying to one or more pieces of apparatus using such a liquid characterized in that one or a plurality of vessels where desired liquid is to be formed visit one or more preparation stations each of which is solely for specified unit operation.
(4) JP-A 198100/95 (tokkai-hei 07-198100)shows a method and an apparatus for shortening the time for changing-over a product fluid to new one, which is made by separating a large pipe line system to several blocks to be able to wash each of the blocks concurrently, and restarting to feed the new product fluid into the block washing of which is completed without waiting for washing of whole pipe line system to be completed.
However, methods disclosed in (2) or (3) demand a large investment for the accompanying facilities and not so flexible to cope with a variety of change of a prescription of the fluid, which easily leads to further investment. Since based on unchanged pipe line, (1) or (4) does not require a lot of investment, but still needs additional pipe lines or connection changes of the complicated pipe line to cope with a variety of prescription changes.
Batch process has another problem to be solved when it is used for manufacturing a large amount of final product which requires amount of component material for the final product prepared by more than several batches. For example, typically in manufacturing photographic material such as photographic film/paper, required total amount of coating liquid, which is a component material for photographic film/paper, reaches several batches amount or up to more than hundred batches.
The problem is that some amount of prepared liquid component material in the batch process is left and wasted when the batch process manufacturing is over because the required total amount is usually not equal to an exact integral multiple of one batch amount. In the case of using expensive material such as emulsion and some additives for photographic coating liquid, the waste should be strictly avoided. It can be thought that amount to be prepared in final batch is adjusted to the fractional amount. However batch process has usually minimum amount to be able to treat because of minimum agitating amount of agitating vessel and/or minimum amount of liquid measuring device and so forth, so it is impossible to do that way if the fractional amount is less than the minimum amount.
An object of the invention is to provide a new designed system for batch process where a plurality of batch processing lines are simultaneously used for making a product, such as simultaneously multi-coated photographic film/paper, which is capable of easily coping with the change of raw materials or prescriptions for the product without increasing or changing existing pipe lines or chemical liquid stock vessels.
Another object of the invention is to provide a method for minimizing a waste of raw material left in batch process where an amount of material corresponding to a plurality of batches is used for manufacturing a final product.
The new designed system includes a plurality of chemical liquid preparation lines, each of which includes one or more multi-purpose primary chemical liquid preparation vessels, one or more multi-purpose chemical liquid stock vessel each of which is connected to each of the multi-purpose primary chemical liquid preparation vessels, one or more chemical liquid measuring device each of which is connected to each of the multi-purpose chemical liquid stock vessels, a single secondary chemical liquid preparation vessel, and piping connected to the chemical liquid measuring devices to feed the chemical liquid in the chemical liquid stock vessels to the single secondary chemical liquid preparation vessel. A required change of the chemical liquid can be made by replacing the chemical liquid in each of the vessels with new ones without affecting another chemical liquid preparation line in changing prescription for the following downstream process.
In the preferred embodiment, the system includes a common chemical liquid preparation vessel for preparing common chemical liquid used in the plural chemical liquid preparation lines, a common chemical liquid stock vessel connected to the common chemical liquid preparation vessel, and piping connected to the common chemical liquid stock vessel with branches for feeding the common chemical liquid into each of the secondary chemical liquid preparation vessels.
The method for minimizing a waste of raw material includes the following steps:
calculating a necessary amount (A) of the material for the following process; and
determining a real amount (B) to be prepared in the following batch process by use of a maximum amount per one batch process M-max, a minimum amount per one batch process M-min, and a standard amount M-st that is determined between the maximum amount M-max and the minimum amount M-min.
If the necessary amount (A) is more than twice standard amount M-st, the real amount (B) is determined as the standard amount M-st. If the necessary amount (A) is between twice standard amount and a maximum amount M-max, the real amount (B) is determined as a half of the necessary amount (A)/2. If the necessary amount (A) is between the maximum amount M-max and the minimum amount M-min, the real amount (B) is determined as the necessary amount (A). If the necessary amount (A) is less than the minimum amount M-min, real amount (B) is determined as the minimum amount M-min.